[Devel] [PATCH RHEL7 COMMIT] ms/KVM: nVMX: Do not load EOI-exitmap while running L2
Konstantin Khorenko
khorenko at virtuozzo.com
Tue Apr 30 13:49:57 MSK 2019
The commit is pushed to "branch-rh7-3.10.0-957.12.1.vz7.95.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-957.12.1.vz7.95.2
------>
commit 1a6ef78b6f9cf97662c8ab3c5784aebaec9cfba6
Author: Liran Alon <liran.alon at oracle.com>
Date: Tue Apr 30 13:49:54 2019 +0300
ms/KVM: nVMX: Do not load EOI-exitmap while running L2
When L1 IOAPIC redirection-table is written, a request of
KVM_REQ_SCAN_IOAPIC is set on all vCPUs. This is done such that
all vCPUs will now recalc their IOAPIC handled vectors and load
it to their EOI-exitmap.
However, it could be that one of the vCPUs is currently running
L2. In this case, load_eoi_exitmap() will be called which would
write to vmcs02->eoi_exit_bitmap, which is wrong because
vmcs02->eoi_exit_bitmap should always be equal to
vmcs12->eoi_exit_bitmap. Furthermore, at this point
KVM_REQ_SCAN_IOAPIC was already consumed and therefore we will
never update vmcs01->eoi_exit_bitmap. This could lead to remote_irr
of some IOAPIC level-triggered entry to remain set forever.
Fix this issue by delaying the load of EOI-exitmap to when vCPU
is running L1.
One may wonder why not just delay entire KVM_REQ_SCAN_IOAPIC
processing to when vCPU is running L1. This is done in order to handle
correctly the case where LAPIC & IO-APIC of L1 is pass-throughed into
L2. In this case, vmcs12->virtual_interrupt_delivery should be 0. In
current nVMX implementation, that results in
vmcs02->virtual_interrupt_delivery to also be 0. Thus,
vmcs02->eoi_exit_bitmap is not used. Therefore, every L2 EOI cause
a #VMExit into L0 (either on MSR_WRITE to x2APIC MSR or
APIC_ACCESS/APIC_WRITE/EPT_MISCONFIG to APIC MMIO page).
In order for such L2 EOI to be broadcasted, if needed, from LAPIC
to IO-APIC, vcpu->arch.ioapic_handled_vectors must be updated
while L2 is running. Therefore, patch makes sure to delay only the
loading of EOI-exitmap but not the update of
vcpu->arch.ioapic_handled_vectors.
Reviewed-by: Arbel Moshe <arbel.moshe at oracle.com>
Reviewed-by: Krish Sadhukhan <krish.sadhukhan at oracle.com>
Signed-off-by: Liran Alon <liran.alon at oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
https://jira.sw.ru/browse/PSBM-93945
(cherry picked from commit e40ff1d6608dd9a5e07d7bc3079c64d9d676fe15)
Signed-off-by: Jan Dakinevich <jan.dakinevich at virtuozzo.com>
---
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/kvm_cache_regs.h | 5 +++++
arch/x86/kvm/x86.c | 18 ++++++++++++++++--
include/linux/kvm_host.h | 1 +
4 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index fb1075221916..969d4bc54258 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -468,6 +468,7 @@ struct kvm_vcpu_arch {
u64 apic_base;
struct kvm_lapic *apic; /* kernel irqchip context */
bool apicv_active;
+ bool load_eoi_exitmap_pending;
DECLARE_BITMAP(ioapic_handled_vectors, 256);
unsigned long apic_attention;
int32_t apic_arb_prio;
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index e1e89ee4af75..ac7bb1429491 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -92,6 +92,11 @@ static inline void enter_guest_mode(struct kvm_vcpu *vcpu)
static inline void leave_guest_mode(struct kvm_vcpu *vcpu)
{
vcpu->arch.hflags &= ~HF_GUEST_MASK;
+
+ if (vcpu->arch.load_eoi_exitmap_pending) {
+ vcpu->arch.load_eoi_exitmap_pending = false;
+ kvm_make_request(KVM_REQ_LOAD_EOI_EXITMAP, vcpu);
+ }
}
static inline bool is_guest_mode(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c075dfe5c015..f1230a251add 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6640,8 +6640,6 @@ static void process_smi(struct kvm_vcpu *vcpu)
static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
{
- u64 eoi_exit_bitmap[4];
-
if (!kvm_apic_hw_enabled(vcpu->arch.apic))
return;
@@ -6655,6 +6653,20 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
if (ioapic_in_kernel(vcpu->kvm))
kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
}
+
+ if (is_guest_mode(vcpu))
+ vcpu->arch.load_eoi_exitmap_pending = true;
+ else
+ kvm_make_request(KVM_REQ_LOAD_EOI_EXITMAP, vcpu);
+}
+
+static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu)
+{
+ u64 eoi_exit_bitmap[4];
+
+ if (!kvm_apic_hw_enabled(vcpu->arch.apic))
+ return;
+
bitmap_or((ulong *)eoi_exit_bitmap, vcpu->arch.ioapic_handled_vectors,
vcpu_to_synic(vcpu)->vec_bitmap, 256);
kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
@@ -6776,6 +6788,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
}
if (kvm_check_request(KVM_REQ_SCAN_IOAPIC, vcpu))
vcpu_scan_ioapic(vcpu);
+ if (kvm_check_request(KVM_REQ_LOAD_EOI_EXITMAP, vcpu))
+ vcpu_load_eoi_exitmap(vcpu);
if (kvm_check_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu))
kvm_vcpu_reload_apic_access_page(vcpu);
if (kvm_check_request(KVM_REQ_HV_CRASH, vcpu)) {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5fb0e2efa4b0..ff50020dc91f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -152,6 +152,7 @@ static inline bool is_error_page(struct page *page)
#define KVM_REQ_HV_RESET 29
#define KVM_REQ_HV_EXIT 30
#define KVM_REQ_HV_STIMER 31
+#define KVM_REQ_LOAD_EOI_EXITMAP 32
#define KVM_USERSPACE_IRQ_SOURCE_ID 0
#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1
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